Starter apparatus for pulse jet burners



Feb. 16, 1965 F. HAAG ETAL 3,169,570

STARTER APPARATUS FOR PULSE JET BURNERS Filed Nov. 15, 1963 /A/ new 70R5 United States Patent 7 aisasrs Patented Feb. 16, 1965 3,169,570STARTER APEARATUfi FGR PULSE JET BURNER Franz Haag, Piochingen(Neclrar), md Ludwig Huber, Suittgart-Mohriugen, Germany, assignors toJunkers & Qo. G.m.h.H., Wernau (Neckar), Germany Filed Nov. 13, 1963,Ser. No. 323,473 Claims priority, application Germany, Nov. 15, 1952,

19 Claims, Roi. 153-4 The present invention relates to pulse jet burnersin general, and more particularly to a novel starter apparatus for pulsejet burners.

The operation of a pulse jet burner is based on the principle that amixture of fuel and oxygen which is admitted into a combustion chamberis ignited when the burner is started and that, following the explosion,a sound wave and a column of gases will travel down a resonance ductwhereby a partial vacuum is induced in the suction duct to draw a newsupply of mixture which is ignited in a fully automatic way by residualframe so that the explosions follow each other in rapid sequence.Certain difficulties arise if the mixture of fuel with oxygen or 01-:gen-containing air is unsatisfactory so that the igniter fails toinitiate an explosion in the combustion chamber. For example, variationsin voltage may cause fluctuations in the percentage of oxygen in themixture which is formed in the suction duct, and such fluctuations inthe percentage of oxygen affect the percentage of fuel. Also, if thecalorific value of fuel is not uniform, the percentage of oxygen in themixture must be adjusted accordingly. Furthermore, the density andpressure of fuel may fluctuate within a rather wide range so that themixture might not be ignited at the time it enters the combustionchamber of the pulse jet burner. In the absence of ignition, the mixtureof fuel with oxygen fills the interior of the pulse jet burner includingthe combustion chamber and the customary sound absorbing chambers whichcommunicate with suction and resonance ducts. If the ignition issuccessful in the next attempt, the mixture filling the interior of thepulse jet burner will produce excessive noise which is comparable to thenoise of an automotive vehicle when its engine misfires.

Accordingly, it is an important object of the present invention toprovide a novel starter apparatus for pulse jet burners which avoids thedrawbacks of conventional starter apparatus and which can be readilyinstalled on presently used pulse jet burners in water heating and/ orair heating systems of one-family or multi-family dwellings and similarestablishments.

Another obg ect of the invention is to provide a starter apparatus whichautomatically inactivates the igniter if the pulse jet burner fails tooperate after one or more false starts so that the person in charge willbecome aware of and will be in a position to correct the defect.

A further object of the invention is to provide a starter apparatuswhich automatically shuts ofi the flow of fuel to the pulse jet burnerif the igniter fails to initiate an explosion of the mixture in thecombustion chamber.

A concomitant object of the invention is to provide a starter apparatusfor use in a pulse jet burner whose suction duct receives air from acompressor and to construct the starter apparatus in such a way that thecompressor is automatically arrested if the igniter fails to start thepulse jet burner.

Still another object of the invention is to provide a starter apparatuswhich is constructed and assembled in such a way that it automaticallyinitiates the delivery of oxygen and fuel to the suction duct of a pulsejet burner in response to circulation of air or water which is to beheated by the burner.

An additional object of the invention is to provide an improvedattachment consisting of a plurality of valves which constitutes acomponent part of the improved starter apparatus and which may becombined with many types of existing pulse jet burners withoutnecessitating substantial modifications in the construction and/ormounting of such burners.

A further object of the invention is to provide a starter apparatuswhich is more reliable than all such starter apparatus of which we haveknowledge at this time, which is especially suited for use in pulse jetburners in water heating systems, and in which all parts are read lyaccessible for convenient inspection or replacement.

A concomitant object of the invention is to provide a starter apparatuswhich is constructed and assembled in such a way that the suction ductof the pulse jet burner cannot receive any fuel unless the compressordelivers a stream of oxygen or oxygen-containing air.

With the above objects in view, one feature of our invention resides inthe provision of a pulse jet burner which compr' es a combustion chamberincluding a suction duct arranged to form a mixture of fuel with oxygenand a resonance duct for discharging the products of combustiondeveloping on combustion of such mixture in the combustion chamber, afuel supply conduit connected with thsuction duct, and a starterapparatus which comprises a first valve including a first pressureresponsive element movable between a plurality of positions, a firstline connecting this valve with the fuel supply conduit so that thepressure of fuel may move the first pressure responsive element to afirst position, a second line connecting the valve with the suction ductso that the pressure of the mixture in the suction duct may move thepressure responsive element to a second position, an electric starterswitch operatively connected with the pressure responsive element tocomplete an el ctric circuit when the pressure responsive element ismoved to its first position, a compressor comprising an electric motorconnected in circuit with the starter switch to deliver oxygen to thesuction duct when the starter switch completes the circuit, an electricigniter connected in circuit with the starter switch to ignite themixture in the combustion chamber when the starter switch completes thecircuit, a second valve provided in the fuel supply conduit andincluding a second pressure responsive element which is movable betweena plurality of positions, and a third line connecting the second valvewith the compressor to move the second pressure responsive element to afirst position in response to changes in pressure generated by thecompressor. The second pressure responsive element is movable to asecond position by the pressure of fuel in the supply conduit, and thestarter apparatus further comprises a regulator valve provided in thefuel supply conduit upstream of the second valve and operativelyconnected with the second pressure responsive element to permit flow offuel to the suction duet when the second pressure responsive elementmoves to its first positron.

We prefer to provide a manually operable shutoff valve which is mountedin the fuel supply conduit upstream of the regulator valve, and a safetyvalve which is provided in this conduit between the shutoff valve andthe regulator valve.

The novel features which are considered as characteristic of theinvention are set forth in particular in the appended claims. Theimproved starter apparatus itself, however, both as to its constructionand its method of operation, together with additional features andadvantages thereof, will be best understood upon perusal of thefollowing detailed description of a specific embodiment with referenceto the accompanying drawings the J single illustration of which is asomewhat schematic section through a pulse jet burner which embodies thestarter apparatus of our invention.

Referring to the drawings the pulse jet burner comprises a combustionchamber it? including a suction duct 11 and a resonance duct 12. Theresonance duct discharges into a sound absorbing chamber 13 which isprovided with a take-off pipe 14 serving to convey spent gases whichdevelop on combustion of a fuel-o: ygen mixture delivered by the suctionduct 11. The suction duct has a first inlet 15 for oxygen oroxygencontaining air, and this inlet is controlled by a controlled valve3.5a which is normally open. The entire suction duct 11 is surrounded bya second sound absorbing chamber 17 which cooperates with the chamber 13to reduce noise when the pulse jet burner is in actual use. The chamber17 commun cates with the pressure side of an air compressor here shownas a blower 32 whose suction side communicates with the atmospherethrough a nipple Thus, oxygen or oxygen-containing air which is admittedthrough the inlet 15' must flow through the nipple 13 to be compressedby the blower 32 and to enter the charnber 17 on its way into thesuction duct 11.

The inlet 16 communicates with a portion 19' of a main fuel supplyconduit 19 which is connected to a suitable source of compressed gaseousfuel, not shown. The conduit 1 accommodates a manually operable shutoffvalve 2%) having a handle 29:; which may be grasped by hand. The valvemember of this shutoff valve is biased by a spring 2% and may bearrested in selected positions of axial adjustment to regulate theadmission of fuel at the will of the operator.

In the illustrated embodiment, the pulse jet burner serves to heat astream of water which is admitted through a cold water pipe 23 and flowsthrough a heating pipe 23 which is coiled around the heat-radiatingparts of the burner (i.e., about the resonance duct 12 and combustionchamber 10). The heating pipe 23 discharges into a hot Water pipe 24which is provided with a faucet 25'. The cold water pipe 21 contains atapping device 22 similar to those disclosed, for example, in US.Patents Nos. 2,258,- 590 and 2,763,244. This tapping device comprises aflexible diaphragm 26 which controls a safety valve 27 provided in thefuel supply conduit 19 downstream of the shutoff valve 2%. As shown, thevalve member 27a of the safety valve 27 is connected with the diaphragm26 so that any flexion of the diaphragm will cause correspondingadjustments in the position of the valve members 270. This valve memberis biased to scaling position by a resilient element here shown as avalve spring 271). If the liquid flowing in the pipes 21, 23, 24 is tobe heated to elevated temperature, at least a portion of the heatingpipe 23 may extend through the combustion chamber 19.

In accordance with one feature of the present invention, we provide twopressure responsive valves including a first valve 39 and a second valve46. The housing of the valve 30 defines two compartments 36, the firstof which communicates with the suction duct 11 through a line 5% and thesecond of which communicates with the fuel supply conduit 19 through abypass line 31 whose intake is connected with the conduit 19 at a pointdownstream of the safety valve 27. The compartment 36 accommodates astarter switch 37, here shown as a mercury switch, which is connected incircuit with the electric motor 32a of the blower 32 and with anelectric igniter 33 which is a sparkplug extending into the interior ofthe combustion chamber 1t) and serving to ignite the mixture deliveredby the suction duct 11.

The second pressure responsive valve 4i) comprises a housing whichdefines two separate compartments 45. The compartment 44 communicateswith a line 41 leading to the pressure side of the blower 32. Thecompartment 4-5 forms a passage for the flow of fuel from the ll mainfuel supply conduit 19 (downstream of the safety valve 27) to theportion 19 which leads to the inlet 16. This second pressure responsivevalve 4t? further comprises a pressure responsive element here shown asa flexible diaphragm 43 which separates the compartment 44 from thecompartment 45 and which is connected with the stem 42' of a regulatorvalve 42 serving to control the flow of fuel from the main conduit 19into the compartment 45. It will be noted that the regulator valve 42 islocated downstream of the intake end of the bypass line 3-1. Thehousings of the valves 30, 4% are coaxial and have a common wall 51, andanother wall 52 of the valve 4% defines a seat 53 for the regulatorvalve 42. The stem 42 is coaxial with the housings of the valves 3%, 4G.

The compartments 35, 3-6 of the valve 3 are separated by a pressureresponsive element here shown as a flexible diaphragm 34 whose peripheryis clamped to the housing of this valve. The switch 37 is pivotable andnormally rests on the median portion of the diaphragm 34 to be pivotedin a clockwise direction, as viewed in the drawings, when the pressurein compartment 35 rises so that the median portion of the diaphragm 34is flexed upwardly. The switch 37 is a mercury-containing tube whichwill complete the circuit of the blower motor 32a and igniter 33 whenthe diaphragm is flexed in a sense to reduce the volume of thecompartment 36. The line 50 is connected with the suction duct 11 at apoint downstream of the inlets 15 and 16 so that pressure prevailing inthe compartment 36 corresponds to the pressure of the mixture which isbeing delivered to the combustion chamber 10.

The pulse jet burner of our invention operates as follows:

The operator opens the shutoff valve 2% in the fuel supply conduit 1?and the faucet 25 in the hot water pipe 24. Thus, a stream of water canflow from the cold water pipe 21 through the tapping device 22 wherebythe stream flexes the diaphragm 26 and moves the valve member of thesafety valve 27 away from its seat so that fuel entering through theconduit 19 may flow into a space 54. The flow of fuel through this space54 is controlled by the safety valve 27 and regulator valve 42. It willbe noted that the safety valve 27 opens automatically when the tappingdevice 22 is actuated by flowing water, i.e., there can be no flow offuel into the suction duct 11 excepting when a stream of watercirculates in the system including the pipes 21, 23 and 24.

Some fuel entering the space 54 is free to flow into the bypass line 31and to enter the compartment 35. The resulting rise in pressureprevailing in the compart ment 35 causes the diaphragm 34 to flexupwardly and to pivot the starter switch 37 to an operative position inwhich the switch completes the circuit of the blower motor 32a andigniter 33. The blower 32 now delivers a stream of compressed air intothe chamber 17 and into the line 41. The pressure of air flowing in theline 41 raises the pressure in the compartment 44- to flex the diaphragm43 downwardly, as viewed in the drawings, whereby the regulator valve 42moves away from the seat 53 and allows fuel to enter the conduit portion123' which conveys the fuel to the inlet 1 The thus admitted stream offuel is mixed with compressed air which is delivered through the inlet15 and forms with such air a mixture which enters the combustion chamber10 to be ignited by the igniter 33. This starts the operation of thepulse jet burner whereby the resulting explosion produces a pressurewave which expels combustion products through the resonance duct 12.This pressure wave is felt in the line 5% and hence in the compartment36 so that the diaphragm 34 is flexed downwardly and the starter switch37 opens the circuit of the igniter 33 and blower motor 32a. If thepulse jet burner operates properly, the igniter and the bl Wer mayremain in inoperative condition because the combustion chamber 10 willautomatically draw a mixture of fuel and air and such mixture will beignited automatically as soon as it enters the combustion chamber. Inother words, as long as the burner operates properly, a singlecompression and a single ignition will suffice to start the operation.

It will be noted that, When the operation is to begin, the suction duct11 can receive fuel only if the blower 32 sends a stream of compressedair through the line 41 to open the regulator valve 42. In other words,no fuel will enter the suction duct 11 unless the blower 32 deliversoxygen through the inlet 15. The control valves 15a, 16:: will beadjusted if the operator finds that the mixture in the duct 11 isunsatisfactory.

The pressure of air in the line 41 rises from Zero to a pressure whichexceeds the pressure of fuel in the space 54 so that the blower 32 willbe in a position to cause movement of the diaphragm 43 against thepressure prevailing in the space 54 and to open the regulator valve 42.When the burner is in operation, pressure Waves alternate with suctionwaves and the regulator valve 42 opens in a fully automatic way at suchfrequency that the suction duct receives fuel at requisite intervals.

If the pulse jet burner fails to operate in the aforedescribed manner,for example, if the proportion of oxygen and fuel in the fixtureentering the combustion chamber is such that the mixture is not ignitedwhen the circuit of the igniter 33 is completed, static pressure of thenon-combusted mixture which fills the combustion chamber 16 and thesuction duct 11 is communicated through the line 5% so that the starterswitch 37 returns to its idle position and opens the circuit of theblower motor 32a and igniter 33. In other words, regardless of Whetherthe mixture is ignited or not, the starter switch 37 will open theelectric circuit and will arrest the blower 32. When the blower isarrested, pressure in the line 41 drops so that the diaphragm 43 returnsthe regulator valve 42 to sealing position in which this valve engagesthe seat 53 and seals the compartment 45 from the space 54. p

The same operation is now repeated in the aforedescribed sequence, i.e.the pressure in the space 54 rises as soon as the regulator valve 42moves against the seat 53 whereby the bypass line 31 sends a stream offuel into the compartment 35 to flex the diaphragm 34 and to move thestarter switch 37 into an operative position in which the switchcompletes the electric circuit of the blower motor 32a and igniter 33.The blower 32 sends a stream of air through the line 41 to flex thediaphragm 43 downwardly and to move the regulator valve 42 away from theseat 53 whereby the main fuel supply conduit 19 communicates withthetconduit portion 1g and the latter admits into the suction duct 11 astream of fuel which is mixed with air delivered by the blower 32 viachamber 17 and inlet 15. This mixture is ignited by the igniter 33whereupon the pulse jet burner operates in a fully automatic way.

If the mixture is not ignited, the same operation repeats itself as longas necessary to start the burner. Inaccordance with another feature ofthe invention, we provide a thermoelectric safety switch 56 which isconnected in the circuit 55 of a current source 58, blower motor 32::and igniter 33. This thermoelectric safety switch 56 is of well knownconstruction and is adjusted in such a way that it opens the circuit 55if the julse jet burner fails to operate after a series of false starts,for example, after 68 consecutive completions of the circuit 55. Thisindicates to the operator that the burner cannot produce a satisfactoryfuel-air mixture and that the system requires overhauling or adjustment(e.g., an adjustment of valves a, 16a). Thus, the switch 56 serves as asafety device which prevents escape of fuel'even if the tapping device22 permits fuel to flow into the space 54 and compartment 35.

In the illustrated embodiment, the tapping device 22 and the pressureresponsive switches are combined into a unitary attachment which may besecured to a pulse jet burna K? er. Such construction has manyadvantages, particularly as regards savings in time for connecting ordisconnecting the attachment from a burner, but is not absolutelynecessary. Thus, it is equally possible to combine the tapping device 22and the safety valve 27 into a first unit and to mount this first unitindependently of the unit including the pressure responsive valves 36,49. Furthermore, the valves 30, 40 may be bodily separated from eachother in that the common wall 51 may be replaced by two separate walls.It is further to be noted that the compartment 45 need not serve as apassage for fuel into the conduit portion 19- because the outlet fromthe space 54 may be connected directly with the inlet of the conduitportion 19' as long as this outlet is controlled by the regulator valve42 which in turn receives motion from the diaphragm 43.

The pressure responsive switches 30, 40 may be modified in a number ofways, for example, by replacing the diaphragms 34, 43 with other typesof pressure responsive elements. Also, the valve disk of the regulatorvalve 42 could be accommodated in the compartment 45, Le, the seat 53could be located at the upper side of the wall 52. This wouldnecessitate replacing the line 41 by a line whose intake end would beconnected with the suction side of the blower 32 so that pressure in thecompartment 44 would be below atmospheric pressure as soon as the blower32 is set in motion.

It is further obvious that the mercury switch 37 maybe replaced by othertypes of starter switches which are capable of completing an electriccircuit in response to pressure of fuel in the valve 30. Finally, thesparkplug of the igniter 33 may be replaced by a glow plug or anothertype of means which is capable of igniting a fuel-oxygen mixture. Allsuch modifications will be readily comprehended by men skilled in thisart without necessitating additional illustrations.

Without further analysis, the foregoing will so fully reveal the gist ofthe present invention that others can, by applying current knowledge,readily adapt it for various applications without omitting featuresthat, from the standpoint of prior art, fairly constitute essentialcharac teristics of the generic and specific aspects of this inventionand, therefore, such adaptations should and are intended to becomprehended within the meaning and range of equivalence of thefollowing claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a pulse jet burner, in combination, a combustion chamber includinga suction duct arranged to form a mixture of fuel with oxygen and aresonance duct for discharging the products developing on combustion ofsuch mixture; a fuel supply conduit connected with said suction duct; afirst valve including a pressure responsive element movable between twopositions; a first line connecting said valve with said supply conduitso that the pressure of fuel may move said element to one of saidpositions; a second line connecting said valve with said suction duct sothat the pressure of said mixture may move said element to the otherposition; an electric starter switch operatively connected with saidpressure responsive element and operative to complete an electriccircuit when said element is moved to said one position; compressormeans comprising electric motor means connected in circuit with saidstarter switch for delivering oxygen into said suction duct in operativeposition of said switch; electric igniter means connected in circuitwith said starter switch for igniting the mixture in said combustionchamber in operative position of said switch; a second valve provided insaid supply conduit and comprising a second pressure responsive elementmovable between two positions; a third line connecting said second valvewith said compressor means to move said second element to one of saidpositions thereof in response to pressure of oxygen generated by saidcompressor means, said second element being movable to the otherposition thereof by the pressure of fuel in saidsupply conduit; and aregulator valve provided in said supply conduit I? upstream of saidsecond valve and operatively connected with said second pressureresponsive element to permit flow of fuel through said second valve andinto said suction duct when said second element moves to said oneposition thereof.

2. In a pulse jet burner, in combination, a combustion chamber includinga suction duct arranged to form a mixture of fuel with oxygen and aresonance duct for discharging the products developing on combustion ofsuch mixture; 21 fuel supply conduit connected with said suction duct; afirst valve including a pressure responsive element movable between twopositions; a first line connecting said valve with said supply conduitso that the pressure of fuel may move said element to one of saidpositions; a second line connecting said valve with said suction duct sothat the pressure of said mixture may move said element to the otherposition; an electric starter switch operatively connected with saidpressure responsive element and operative to complete an electriccircuit when said element is moved to said one position; compressormeans comprising electric motor means connected in circuit with saidstarter switch for delivering oxygen into said suction duct in operativeposition of said switch; electric igniter means connected in circuitwith said starter switch for igniting the mixture in said combustionchamber in operative position of said switch; a second valve provided insaid supply'conduit and comprising a second pressure responsive elementmovable between two positions; a third line connecting said second valvewith said compressor means to move said second element to one of saidpositions thereof in response to pressure of oxygen generated by saidcompressor means, said second element being movable to the otherposition thereof by the pressure of fuel in said supply conduit; aregulator valve provided m said supply conduit upstream of said secondvalve and operatively connected with said second pressure responsiveelement to permit flow of fuel through said second valve and into saidsuction duct when said second element moves to said one positionthereof; and a manually operated shutofi valve provided in said fuelsupply conduit upstream of said regulator valve.

3. A combination as set forth in claim 2, further comprising pipe meansarranged to convey a fluid to be heated by exchange of heat with saidcombustion chamher, a tapping device provided in said pipe means, and asafety valve provided in said fuel supply conduit between said shutotfvalve and said regulator valve and arranged to open when said tappingdevice permits flow of a fluid through said pipe means.

4. A combination as set forth in claim 3, wherein said tapping devicecomprises a diaphragm which is flexed by fluid in said pipe means andwherein said safety valve comprises a valve member secured to saiddiaphragm and movable between an open and a sealing position, andresilient means arranged to bias said valve member to said sealingposition.

5. In a pulse jet burner, in combination, a combustion chamber includinga suction duct arranged to form a mixture of fuel with oxygen and aresonance duct .for discharging the products developing on combustion ofsuch mixture; 21 fuel supply conduit connected with said suction duct; afirst valve including a first pressure responsive element movablebetween two positions; a first line connecting said valve with saidsupply conduit so that the pressure of fuel may move said pressureresponsive element to one of said positions; a second line connectingsaid valve with said suction duct so that the pressure of said mixturemay move said pressure element to the other position; an electric switchoperatively connected with said pressure responsive element andoperative to complete an electric circuit when said element is moved tosaid one position; compressor means comprising electric motor meansconnected in circuit with 7 said switch for delivering oxygen into saidsuction duct in operative position of said switch; a second valveprovided in said supply conduit and comprising a second pressureresponsive element movable between two positions; a third lineconnecting said second valve with said compressor means to move saidsecond element to one of said positions thereof in response to pressureof oxygen generated by said compressor means, said second element beingmovable to the other position thereof by the pressure of fuel in saidsupply conduit; and a regulator valve provided in said supply conduitupstream of said second valve and operatively connected with said secondpressure responsive element to permit flow of fuel through said secondvalve and into said suction duct when said second element moves to saidone position thereof.

6. A combination as set forth in claim 5, further comprising a shutoffvalve provided in said fuel supply conduit upstream of said regulatorvalve.

7. A combination as set forth in claim 5, wherein said first valvecomprises a housing and wherein said first pressure responsive elementis a flexible diaphragm dividing the interior of said housing into afirst and second compartment respectively communicating with said firstand second lines.

8. A combination as set forth in claim 7, wherein said switch is mountedin said second compartment and is arranged to complete said electriccircuit when said diaphragm is flexed in response to rising pressure insaid first compartment.

9. A combination as set forth in claim 5, wherein said second valvecomprises a housing and wherein said second pressure responsive elementis a flexible diaphragm dividing the interior of said housing into apair of compartments one of which communicates with said third line andthe other of which constitutes a passage in said fuel supply conduit,said fuel supply conduit having a first portion for delivering fuel tosaid passage and a second portion for delivering fuel from said passageto said suction duct, said regulator valve being arranged to control theflow of fuel from said first portion of said fuel supply conduit to saidpassage.

10. A combination as set forth in claim 9, wherein the housing of saidsecond valve has an apertured wall defining a seat through which fuelmay flow into said passage, said regulator valve comprising a valvemember connected with said diaphragm and arranged to move into sealingengagement with said seat when said first portion of said fuel supplyconduit delivers fuel to said passage and when said compressor means isidle so that fuel in said passage flexes said diaphragm in a directionto reduce the volume of said one compartment.

11. A combination as set forth in claim 5, wherein each of said firstand second valves comprises a housing and wherein said housings have acommon wall, each of said pressure responsive elements comprising aflexible diaphragm which divides the interior of the respective housinginto a pair of compartments, said housings having a common axis and saidregulator valve comprising a valve member reciprocable in the axialdirection of said housings and a valve stem secured to the diaphragm ofsaid second valve.

12. A combination as set forth in claim 11, wherein one compartment ofsaid second valve constitutes a passage in which the fuel flows to saidsuction duct in response to opening of said regulator valve.

13. In a pulse jet burner, in combination, a combustion chamberincluding a suction duct arranged to form a mixture of fuel with oxygenand a resonance duct for discharging the products developing oncombustion of such mixture; a fuel supply conduit connected with saidsuction duct; a first valve including a first pressure re sponsiveelement movable between two positions; a first line connecting saidvalve with said supply conduit so that the pressure of fuel may movesaid first element to one of said positions; a second line connectingsaid valve with said suction duct so that the pressure of said mixturemay move said first element to the other position; an electric starterswitch operatively connected with said first element and operative tocomplete an electric circuit when said first element is moved to saidone position; compressor means comprising electric motor means connectedin circuit with said starter switch for delivering oxygen into saidsuction duct in operative position of said starter switch; electricigniter means connected in circuit with said starter switch for ignitingthe mixture in said combustion chamber in operative position of saidstarter switch; a safety switch provided in and arranged to open saidcircuit in response to repeated movements of said starter switch to openposition; a second valve provided in said supply conduit and comprisinga second pressure responsive element movable between two positions; athird line connecting said second valve with said compressor means tomove said second element to one of said positions thereof in response topressure of oxygen generated by said compressor means, said secondelement being movable to the other position thereof by the pressure offuel in said supply conduit; and a regulator valve provided in saidsupply conduit upstream of said second valve and operatively connectedwith said second pressure responsive element to permit flow of fuel intosaid suction duct when said second element moves to said one positionthereof.

14. A combination as set forth in claim 13, wherein said safety switchis a thermoelectric switch which opens said electric circuit in responseto a predetermined number of movements of said starter switch to saidoperative position thereof.

15. In a pulse jet burner, in combination, a combustion chamberincluding a suction duct arranged to form a mixture of fuel with oxygenand a resonance duct for discharging the products developing oncombustion of such mixture; a fuel supply conduit connected with saidsuction duct; a first valve including a first pressure responsiveelement movable between two positions; a first line connecting saidvalve with said supply conduit so that the pressure of fuel may movesaid first element to one of said positions; a second line connectingsaid valve with said suction duct so that the pressure of said mixturemay move said first element to the other position; an electric starterswitch operatively connected with said element and operative to completean electric circuit when said first element is moved to said oneposition; compressor means comprising electric motor means connected incircuit with said switch for delivering oxygen into said suction duct inoperative position of said switch; electric igniter means connected incircuit with said switch for igniting the mixture in said combustionchamber in operative position of said switch; a second valve provided insaid supply conduit and comprising a second pressure responsive elementmovable between two positions; a third line connecting said second valvewith said compressor means to move said second element to one of saidpositions thereof in response to variations in pressure generated bysaid compressor means, said second element being movable to the otherposition thereof by the pressure of fuel in said supply conduit; and aregulator valve provided in said supply conduit upstream of said secondvalve and operatively connected with said second pressure responsiveelement to permit flow of fuel into said suction duct when said secondelement moves to said one position thereof, said regulator valve beingarranged to seal said suction duct from said fuel supply conduit whensaid compressor means is idle.

16. In a pulse jet burner, in combination, a combustion chamberincluding a suction duct arranged to form a mixture of fuel with oxygenand a resonance duct for discharging the products developing oncombustion of such mixture; a fuel supply conduit connected with saidsuction duct; and a starting apparatus comprising a first valveincluding a first pressure responsive element movable between twopositions, a first line connecting said valve with said supply conduitso that the pressure of fuel may move said first element to one of saidpositions, a second line connecting said valve with said suction duct sothat the pressure of said mixture may move said first element to theother position, an electric starter switch operatively connected withsaid first element and operative to complete an electric circuit whensaid first element is moved to said one position, compressor meanscomprising electric motor means connected in circuit with said starterswitch for delivering oxygen into said suction duct in operativeposition of said starter switch, electric igniter means connected incircuit with said starter switch for igniting the mixture in saidcombustion chamber in operative position of said starter switch, asecond valve provided in said supply conduit and comprising a secondpressure responsive element movable between two positions, a third lineconnecting said second valve with said compressor means to move saidsecond element to one of said positions thereof in response to pressureof oxygen generated by said compressor means, said second element beingmovable to the other position thereof by the pressure of fuel in saidsupply conduit, a regulator valve provided in said supply conduitupstream of said second valve and operatively connected with said secondpressure responsive element to permit flow of fuel into said suctionduct when said second element moves to said one position thereof, ashutoff valve provided in said fuel supply conduit upstream of saidregulator valve, and a safety valve provided in said fuel supply conduitbetween said shutoff valve and said regulator valve.

17. A combination as set forth in claim 16, further comprising controlvalves provided to adjust the flow of fuel and oxygen to said suctionduct.

18. A combination as set forth in claim 16, wherein said igniter meanscomprise an electric sparkplug extending into said combustion chamber.

19. A combination as set forth in claim 16, further comprising a soundabsorbing housing surrounding said suction duct, said suction ducthaving a first inlet to receive oxygen from said compressor means viasaid housing and a second inlet, said fuel supply conduit having aportion connecting said second valve with said second inlet.

References Cited by the Examiner UNITED STATES PATENTS 416,413 12/89Meyers 158-422 X 2,838,102 6/53 Reimers 158-4 2,962,094 11/60 Wallace158-42.2 X

JAMES W. WESTHAVER, Primary Examiner.

MEYER PERLIN, Examiner.

1. IN A PULSE JET BURNER, IN COMBINATION, A COMBUSTION CHAMBER INCLUDINGA SUCTION DUCT ARRANGED TO FORM A MIXTURE OF FUEL WITH OXYGEN AND ARESONANCE DUCT FOR DISCHARGING THE PRODUCTS DEVELOPING ON COMBUSTION OFSUCH MIXTURE; A FUEL SUPPLY CONDUIT CONNECTED WITH SAID SUCTION DUCT; AFIRST VALVE INCLUDING A PRESSURE RESPONSIVE ELEMENT MOVABLE BETWEEN TWOPOSITIONS; A FIRST LINE CONNECTING SAID VALVE WITH SAID SUPPLY CONDUITSOTHAT THE PRESSURE OF FUEL MAY MOVE SAID ELEMENT TO ONE OF SAIDPOSITIONS; A SECOND LINE CONNECTING SAID VALVE WITH SAID SUCTION DUCT SOTHAT THE PRESSURE OF SAID MIXTURE MAY MOVE SAID ELEMENT TO THE OTHERPOSITION; AN ELECTRIC STARTER SWITCH OPERATIVELY CONNECTED WITH SAIDPRESSURE RESPONSIVE ELEMENT AND OPERATIVE TO COMPLETE AN ELECTRICCIRCUIT WHEN SAID ELEMENT IS MOVED TO SAID ONE POSITION; COMPRESSORMEANS COMPRISING ELECTRIC MOTOR MEANS CONNECTED IN CIRCUIT WITH SAIDSTARTER SWITCH FOR DELIVERING OXYGEN INTO SAID SUCTION DUCT IN OPERATIVEPOSITION OF SAID SWITCH; ELECTRIC IGNITER MEANS CONNECTED IN CIRCUITWITH SAID STARTER SWITCH FOR IGNITING THE MIXTURE IN SAID COMBUSTIONCHAMBER IN OPERATIVE POSITION OF SAID SWITCH; A SECOND VALVE PROVIDED INSAID SUPPLY CONDUIT AND COMPRISING A SECOND PRESSURE RESPONSIVE ELEMENTMOVABLE BETWEEN TWO POSITIONS; A THIRD LINE CONNECTING SAID SECOND VALVEWITH SAID COMPRESSOR MEANS TO MOVE SAID SECOND ELEMENT TO ONE OF SAIDPOSITIONS THEREOF IN RESPONSE TO PRESSURE OF OXYGEN GENERATED BY SAIDCOMPRESSOR MEANS, SAID SECOND ELEMENT BEING MOVABLE TO THE OTHERPOSITION THEREOF BY THE PRESSURE OF FUEL IN SAID SUPPLY CONDUIT; AND AREGULAR VALVE PROVIDED IN SAID SUPPLY CONDUIT UPSTREAM OF SAID SECONDVALVE AND OPERATIVELY CONNECTED WITH SAID SECOND PRESSURE RESPONSIVEELEMENT TO PERMIT FLOW OF FUEL THROUGH SAID SECOND VALVE AND INTO SAIDSUCTION DUCT WHEN SAID SECOND ELEMENT MOVES TO SAID ONE POSITIONTHEREOF.